Crossed tube furnace and still



July 3l, 1956 A. CAPLAN 2,756,727

CROSSED TUBE FURNACE AND STILL Filed March 28, 1952 Az. EXANDE@ CAQ/ AN,

1N V EN TOR.

T TOQNE Y.

A'lllnited States Patent CRUSSEIB TUBE FURNA'CE AND STILL Alexander Caplan, Los Angeles, Calif. Application March 28, 1952, Serial No. 279,121 '7 Ciaims. (Cl. 122-359) This invention relates to a heating furnace for use in the distillation of petroleum. More particularly, the invention relates to a tube type of still wherein oil under pressure is pumped through a series of interconnected tubes disposed in a furnace for rapidly and controllably heating crude oil, or the like, to a desired temperature.

The eiiiciency of a tube still is directly related to the number, size and placement of the tubes. Prior tubes stills included arrangements of interconnected parallel tubes either disposed in a single layer, in a horizontal plane adjacent the top of a rectangular ireboX, or arranged in circular fashion (in cross section) in cylindrical chamber. Usually, only a single layer or bank of tubes was provided because of the substantial reduction in heating efiiciency when a second bank of tubes was disposed above or behind the rst bank of tubes. Eiiiciency of heat radiation is greatly reduced in such an arrangement of two parallel banks of tubes because of the obstructing or blanketing effect created by the iirst bank of tubes, positioned between heat source and the second bank of tubes. In other wo-rds, the first bank of tubes cast a radiant shadow upon the second bank of tubes, resulting in very substantial reduction in heat efliciency.

The several advantages of tube stills over batch or shell type and continuous stills are well known. These advantages include a high average rate of heat transfer, a high rate of flow of oil which results in less decomposition of the oil in the still separation of and ability to make narrow cuts is improved, a greater economy of heat is provided which results in lower operating costs, fire danger is materially lessened because only a small quantity of oil is exposed at one time to the heating means, and the temperature of the oil may be controlled more accurately.

It is the primary object of this invention to design and provide a novel heating furnace or tube still which provides all of the advantages mentioned above and which is more eiiicient than prior tube stills known to me.

An object of this invention is to design and provide a tube still wherein the tubes are so arranged that the number of tubes may be greatly increased while maintaining the heating ethciency which is characteristic of a tube still.

Another object of this invention is to design and provide a tube still wherein a plurality of banks of interconnected tubes are so arranged that heating of each bank of tubes is accomplished in a highly eicient manner.

A further object of this invention is to design and provide a tube type heating furnace wherein a plurality of banks of ytubes are interlaced in such a manner that a tube of either bank does not cast a radiant shadow upon adjacent tubes.

A still further object of this invention is to design and provide a tube type heating furnace wherein the furnace includes a radiation chamber and a convection chamber dened by a horizontal partition Wall, and

2,756,727 Patented July 31, 1956 wherein each chamber is provided with a plurality of banks of interlaced and interconnected tubes.

This invention contemplates a tube type heating furnace wherein two banks of interconnected spaced tubes are crossed as by interlacing at a central portion of a heating chamber, the crossing occurring at a zone immediately below the lower edge of a depending bafe wall.

Generally speaking, this invention contemplates a heating furnace for use in the distillation of petroleum wherein a horizontal partition wall in a iirebox forms a radiant chamber and a convection chamber. ln each chamber are provided two banks of interconnected parallel spaced tubes, each bank lying in an inclined plane opposite to the plane of the other bank and crossing in alternate fashion in a zonelying intermediate the end walls of the tirebox. At the crossing zone, the two banks of tubes are supported by a transversely extending, hollow metal member, and the ends of said banks of tubes may project exteriorly of the end walls of the furnace where suitable connections are made to aiford continuous flow of oil through said tubes. The tube means in the convection chamber are connected to the tube means in the radiant chamber so that a continuous flow of oil is provided first through the convection chamber for initial heating, and then through the radiant chamber for final heating.

Other objects and advantages of this invention will be readily apparent from the following description of the drawings.

In the drawings:

Fig. 1 is a longitudinal sectional View of a heating furnace embodying this invention, the section being taken in a vertical plane indicated by the line I-I of Fig. 3.

Fig. 2 is an end view of the furnace shown in Fig. 1 taken from the plane indicated by line Il-II of Fig. 1.

Fig. 3 is a transverse sectional view taken in the plane indicated by line Ill-III of Fig. 1.

Fig. 4 is a perspective view of the arrangement of interlaced tube banks employed in this invention.

Fig. 5 is a fragmentary, longitudinally sectional view illustrating a modification of the tube arrangement for a heating furnace embodying this invention.

In Fig. 1, a heating furnace of tube type embodying this invention, generally indicated at 10, may comprise a generally rectangular irebox constructed of heat-resistant refractory material as is well known in the art. The furnace 1Q comprises a suitable floor 11, a ceiling or top wall 12, spaced side walls 13 andend walls 14. One of the side walls 13 may be provided with an access door 15 to permit entry into the furnace for cleaning and maintenance purposes.

Each end wall 1d may comprise an outer metal plate 16 and an inner thick section sheet 17 of refractory material. Each end wall is provided with a plurality of spaced openings 18 adapted to receive end portions of tubes used in the still. The openings 18, as viewed in Fig. 2, are arranged in horizontal parallel lines.

Each end wall is provided with an enclosure or header box 19 v,formed of suitable material to accommodate therewithin connecting means for the tubes of the furnace and to protect the ends of said tubes from temperature changes.

A horizontal partition wall 21 extends between end Walls 14 and is disposed approximately midway between the iloor 11 and the top wall 12. The partition wall 21 divides the firebox into a radiant chamber 22 and a convection chamber 23. Adjacent to one end wall 14, the partition wall 21, is formed with an opening 24 permitting flow of combustion gases from the radiant chamber 22 to the convection chamber 23. The partition wall 21 may be supported intermediate its length by a depending baffle wall 25 kprovided intermediate the end walls 14, and extending downwardly from the bottom surface of the partition wall for about one-quarter to one-third the heighth of the radiant chamber. The baffle wall 25 acts to deflect combustion gases in the radiant section so as to provide more uniform distribution of heat therein.

The top wall 12 may likewise be supported intermediate its ends by a transversely depending baie wall 25 generally disposed in the same vertical planar zone as the bafe wall 25 in the radiant chamber. The baille wall 26 in the convection chamber serves to provide for a more uniform distribution of combustion gases which tlow through said convection chamber.

At the end wall 14 opposite to the end Wall adjacent to opening 24 may be provided a source of heat indicated by heating means 28. The heating means may comprise any well-known gas or oil fired burner means and may include either one burner means as illustrated, or a plurality of burner means. Suitable controls are provided exteriorly of the furnace for regulating the heating means 28 as is well known in the art. The heating means 23 ejects hot combustion gases into the radiant chamber for heating by radiation, said gases then owing through the opening Z4 in the horizontal partition wall 21 into the convection chamber. After passing through the convection chamber, the combustion gases are discharged through an outlet duct 29 provided in the top wall 12 generally above the heating means 28. The discharge duct 29 leads to a stack which may be provided with dampener controls as is well known in the art.

The present invention contemplates a novel arrangement of tube means, generally indicated at 31, Fig. 4, in Order to provide a tube still of great eliiciency. The tube means in the radiant chamber and in the convection chamber are virtually the same. For brevity and clarity, only one arrangement of tube means 31 will be described with the tube means in the convection chamber being indicated by prime signs.

The tube means 31 comprises a first bank or set of tubes 32 including a plurality of parallel individual tubes 33 spaced apart slightly more than the external diameter of said individual tubes. The tubes 33 lie in a plane inclined downwardly and extending between the end walls 14. Each tube 33 projects through associated openings 18 in the end walls and into the header boxes 19, said openings 18 being inclined to readily accommodate the tubes. In the header box adjacent tubes 33 are joined togetherby suitable pipe connector or bends 34 to provide continuous ow of oil through said tirst bank of tubes.

Tuberneans 31 also includes a second bank of tubes 35 including a plurality of spaced parallel individual tubes 36 spaced apart slightly more than the external diameter of said tubes. rlhe bank of tubes 3S lie in an inclined plane oppositely directed to the inclined plane of the tube bank 32, each tube bank being disposed at approximately the same angle with respect to a horizontal plane. The individual tubes 36 of the second bank of tubes 35 likewise extend through inclined openings 13 in the end walls for series connection by pipe connectors 37 in the header boxes 19.

The bank of tubes 35 may be connected in series to the bank of tubes 32 by means of a connecting pipe 38 so that continuous ow of oil is provided through the two banks of tubes. The inlet for llow of oil is indicated at 39, Fig. 4, and the outlet is indicated at 40.

It should be particularly noted that individual tubes 36 and 33 are arranged in .alternate fashion in a crossing zone generally indicated at 41, and. that in said crossing zone adjacent tubes 36 and 33 are in closely spaced relation. It will thus be seen that bank of tubes 32 are interlaced with the bankof tubes 35 and the relative positions of individual tubes of each bank are such that a radiant shadow is not cast upon the tubes by adjacent tubes.

The interlacing of the first bank of tubes 32 with the second bank of tubes 35 is accomplished by transversely displacing one bank with respect to the other bank as can be best seen in Figs. 2 and 3. This lateral displacement of the two banks of tubes together with the arrangement of each bank in a plane oppositely inclined to the plane of the second bank results in free circulation of hot gases around each individual tube and effective heating of each tube by radiation without loss of heat efliciency. Radiation shadow may be present in nonappreciable or insignificant amounts at the crossing zone of the two banks of tubes, however, the increase in the number of tubes capable of being used in the tube still is virtually doubled, while heat eticiency of the tube still is virtually maintained.

Tube means 31 and 31 may be further supported within the irebox by means of a transversely extending support member 48 and 4S such as a stainless steel pipe carried by the side walls. Each support member 48 and 48 is spaced slightly below the lower edge of the adjacent respective baie wall 2S and 26 so as to support said tube means 31 and 31 approximately at the respective crossing zone 4l. Each support member 48 and 48' may be hollow and, if desired, cooling air may be passed therethrough to prevent bending of the support member when subjected to heat.

The tube means 31 is connected to the outlet 46 of the tube means 31 by means of a suitable pipe bend or connector A42, Fig. 2. The pipe connector l2 connects to the inlet 39 of tube means 31. The inlet 39' of tube means 31 may be connected to a source of crude oil supply by a pipe run d3, said source of crude oil including a pump for forcing the oil through said tube means under preselected pressures. rEhe discharge outlet 40 of the tube means 31 may be connected to a discharge pipe 4d. Adjacent each of the inlet and the discharge pipe 44 may be provided suitable thermo-coupling means, generally indicated at d5 and 46, for determining the temperature of the oil at the inlet and at the outlet of the furnace.

In Fig. 5 is shown a modified arrangement of the tube means wherein a tube means 51 comprising two banks of tubes 52 and 53 are` interlaced and oppositely inclined as in the prior embodiment of the invention. In this modification, a second tube means 54 is superimposed in selected spaced vertical relation above the tube means 51.

The tube means 54 includes two banks of tubes 55 and 56 interlaced and oppositely inclined. Individual tubes of each bank of tubes 55 and 56 lie vertically above and in parallel relation to corresponding individual tubes of banks of tubes 52 and 53.

The tube means 51 and may be connected in series for continuous flow of oil therethrough. The end connections between individual tubes of each bank of tubes may be readily provided by extending the tubes of one bank beyond the tubes of vertically related bank. Connections between the vertically related banks may be suitably made by citsetting one of the connectors around the other.

It should be noted that this modilied arrangement is illustrated in a convection chamber 57 where the cornbustion gases may readily iiow about the arrangement of spaced tubes to accomplish initial heating by convection. The compact, yet adequately spaced arrangement oftubes of this invention thus aiords the use of more tubes in a selected chamber without Vappreciable loss of heat'eiciency.

It is understood that well known pipe ttings and connectors may be used in the header boxes to connect individual tubes or" each bank so that they may be closely spaced `apart only slightly more than the external diameter of a tube.

It is understood that the crossed tube arrangement of this still may be employed in a vertically arranged furnace having a heat source at the bottom thereof and an opening leading to a stack at the top of the furnace. The longitudinal axis of the crossed tubes means is vertically disposed in such :n arrangement.

The crossed tube still of this invention may be em ployed in a single lheating chamber and may be utilized for various industrial purposes where it is desired to accurately control relatively quick heating of a quantity of fluid which is passed through said tubes.

The improved still of the present invention thus affords a novel tube arrangement for effectively increasing the number of tubes capable of being efficiently employed in the heating furnace and for producing an overall increase in the eiiiciency of the tube still. The two banks of tubes lying in oppositely inclined planes and laterally displaced with respect to each for interlacing of the tube banks provides an arrangement wherein each individual tube has virtually its entire surface presented to the hot combustion gases and is virtually free from radiation shadow.

It is understood various modifications and changes may be made in the tube arrangement and still illustrated, and all such changes coming within the scope of the appended claims are embraced thereby.

I claim:

1. In a heating furnace, the combination of: a furnace structure including spaced side walls joined by end walls, a top wall, and a floor; a horizontal partition wall intermediate the floor and top wall defining a lower radiation chamber and an upper convection chamber; means forming an opening in said partition wall adjacent one end wall for communication between said chambers; heating means in the opposite end wall; outlet means in the top wall of the furnace structure; a depending deflector wall in each chamber extending downwardly from the top surface of each chamber; tube means in each chamber, each tube means comprising a first bank of interconnected parallel tubes lying in an inclined transversely disposed plane extending between end walls and a second bank of interconnected parallel tubes lying in an inclined plane opposite to the plane of the first bank; said banks of tubes crossing in the zone in proximity to and below the adjacent depending deflector wall in alternate relation; a support member for said banks of tubes at said crossing zone; said first bank of tubes being connected in series with the second bank for continuous flow of fluid therethrough; said tube means in said chambers being connected in series.

2. In a heating furnace, the combination of: a furnace structure including spaced side walls joined by end walls, a top wall, and a floor; a horizontal partition wall intermediate the iioor and top wall defining a lower radiation chamber and an upper convection chamber; means forming an opening in said partition wall adjacent one end wall for communication between said chambers; heating means in the opposite end wall; outlet means in the top wall of the furnace structure; a depending deliector wall in each chamber extending downwardly from the top surface of each chamber; tube means in each chamber, each tube means comprising a first bank of interconnected parallel tubes lying in an inclined transversely disposed plane extending between end walls and a second bank of interconnected parallel tubes lying in an inclined plane opposite to the plane of the first bank; the tubes of said banks crossing in a zone below the lower edge of said depending bafe wall; a support member for said banks of tubes at said crossing zone; said first bank of tubes being connected in series with the second bank for continuous fiow of Huid therethrough; and the tube means in said chambers being connected in series.

3. In a heating furnace, the combination of a furnace structure including spaced side walls joined by end walls,

a top wall, and a floor; a horizontal partition wall intermediate the floor and top wall defining a lower radiation chamber and an upper convection chamber; means forming an opening in said partition wall adjacent one end wall for communication between said chambers; heating means in the opposite end wall; outlet means in the top wall of the furnace structure; tube means in said chambers interconnected in series, each tube means comprising a first bank of interconnected parallel tubes lying in an inclined transversely disposed plane extending between end walls and a second bank of interconnected parallel tubes lying in an inclined plane opposite to the plane of the first bank; said banks of tubes being interlaced intermediate'said end walls; a support member for said banks of tubes at said crossing zone; and said first bank of tubes being connected in series with the second bank for continuous flow of fluid therethrough.

4. In a heating furnace, the combination of: a furnace structure including spaced side walls joined by end walls, a top wall, and a iioor; a horizontal partition wall intermediatethe iioor and top wall defining a lower radiation chamber and an upper convection chamber; means forming an opening in said partition wall adjacent one end wall for communication between said chambers; heating means in the opposite end wall; outlet means in the top wall of the furnace structure; tube means in said chamber interconnected in series, each tube means comprising a first bank of interconnected parallel tubes lying in an inclined transversely disposed plane extending between end walls and a second bank of interconnected parallel tubes lying in an inclined plane opposite to the plane of the first bank; said banks of tubes being interlaced inter mediate said end walls; and said first bank of tubes being connected in series with the second bank for continous flow of iiuid therethrough.

5. In a heating furnace, the combination of: a hollow furnace structure including a partition wall providing a radiation chamber and a convection chamber; said partition wall being provided with an opening at one end of the furnace structure for communication between said chambers; heating means at the opposite end of said furnace structure; said furnace structure being provided with outlet means in communication with said convection chamber; and tube means in said chambers interconnected in series and extending in an elongated zone parallel to the partition wall, each tube means comprising a first bank of interconnected parallel tubes lying in an inclined plane and a second bank of interconnected parallel tubes lying in an inclined plane opposite to the plane of said first bank, said first and second banks of tubes being interlaced intermediate their ends, and said first bank being connected in series with the second bank for continuous flow of fluid therethough.

6. In a heating furnace as stated in claim 5 including a deiiector wall within said hollow furnace structure extending transversely of said interleaved banks of tubes adjacent their intersection said wall lying perpendicular to the parallel zone and at one side of the tube means.

7. A heating furnace as stated in claim 5 including a support member for each tube means intermediate their ends.

References Cited in the file of this patent UNITED STATES PATENTS 498,239 Coignet May 30, 1893 840,114 Davis Jan. 1, 1907 1,065,418 Winslow June 24, 1913 1,661,544 Nicholson Mar. 6, 1928 1,788,068 Scott Jan. 6, 1931 2,296,390 Marchant Sept. 22, 1942 2,640,687 Throckmorton June 2, 1953 

